I am a little bit confused by the biological oxidation. It is performed by the release of hydrogen instead of addition oxygen, right? And hydrogen acts as a proton. So why is NAD reduced instead of oxidized when it becomes positive? And following this logic, in biological oxidation are reducers donors, and oxidisers - acceptors of electrons? The respiratory chain carries electrons to the ultimate oxidizer - oxygen but aren't these electrons in fact the positively charged hydrogens from NAD.H2.I know that these is a shambolic sum of questions but I'd be really grateful if you'd find the time to explain their answers to me.Thanks!

The oxidation can be performed by either release of hydrogen or addition of oxygen.NAD+ is oxidized and it can become reduced NADH.Yes, they are. Actually no, they are not, because electrons are not hydrogens. During redox reactions electrons are transferred. The hydrogens in NAD(P)/FAD are there only to make it electroneutral.